Oil well operators have long sought improved techniques for forming a fluid production assembly to seal with a casing string and transmit fluid through a production string to the surface. Most fluid production assemblies seal with a casing string and transmit fluid from the casing string to a production tubing string using a production packer. The production packer seals with the casing string, so that formation fluid flows into the casing string, through the central bore of the production packer, then into the production tubing string which continues to the surface. Various types of production packers have been devised to fulfill this purpose, including those disclosed in U.S. Patents Re 36,525; U.S. Pat. Nos. 4,967,844; 5,267,617; 5,613,560; and 5,738,171.
Also, operators have long desired improved techniques for forming a downhole patch across a tubular which has lost sealing integrity, whether that be due to a previous perforation of the tubular, high wear of the tubular at a specific downhole location, or a complete separation of the tubular. There are times when a screened section of a tubular needs to be sealed off. A tubular patch with a reduced throughbore may then be positioned above and below the zone of the large diameter tubular which lost its sealing integrity, and the reduced diameter tubular then hung off from and sealed at the top and bottom to the outer tubular. In some applications, the patch may be exposed to high thermal temperatures which conventionally reduce the effectiveness of the seal between the tubular patch and the outside tubular. In heavy oil recovery operations, for instance, steam may be injected for several days, weeks or months through the tubular, downward past the patch, and then into a formation.
U.S. Pat. No. 5,348,095 discloses a method of expanding a casing diameter downhole utilizing a hydraulic expansion tool. U.S. Pat. No. 6,021,850 discloses a downhole tool for expanding one tubular against a larger tubular or the borehole. Publication U.S. 2001/0020532 A1 discloses a tool for hanging a liner by pipe expansion. U.S. Pat. No. 6,050,341 discloses a running tool which creates a flow restriction and a retaining member moveable to a retracted position to release by the application of fluid pressure. U.S. Pat. No. 6,250,385 discloses an overlapping expandable liner. A sealable perforating nipple is disclosed in U.S. Pat. No. 5,390,742, and a high expansion diameter packer is disclosed in U.S. Pat. No. 6,041,858. U.S. Pat. No. 5,333,692 discloses seals to seal the annulus between a small diameter and a large diameter tubular. U.S. Pat. No. 3,948,321 discloses a liner with a reinforcing swage which remains downhole when the tool is retrieved to the surface.
Due to problems with the procedure and tools used to expand a smaller diameter tubular into reliable sealing engagement with a larger diameter tubular, many tools have avoided expansion of the tubular and used radially expandable seals to seal the annulus between the small diameter and the large diameter tubular, as disclosed U.S. Pat. No. 5,333,692. Other patents have suggested using irregularly shaped tubular members for the expansion, as disclosed in U.S. Pat. Nos. 5,366,012, 5,494,106, and 5,667,011. U.S. Pat. No. 5,785,120 discloses a tubular patch system with a body and selectively expandable members for use with a corrugated liner patch. U.S. Pat. No. 6,250,385 discloses an overlapping expandable liner. A sealable perforating nipple is disclosed in U.S. Pat. No. 5,390,742 and a high expansion diameter packer is disclosed in U.S. Pat. No. 6,041,858.
Various hydraulic expansion tools and methods have been proposed for expanding an outer tubular while downhole. While some of these tools have met with limited success, a significant disadvantage to these tools is that, if a tool is unable to continue its expansion operation (whether due to the characteristics of a hard formation about the tubular, failure of one or more tool components, or otherwise), it is difficult and expensive to retrieve the tool to the surface to either correct the tool or to utilize a more powerful tool to continue the downhole tubular expansion operation. Accordingly, various techniques have been developed to expand a downhole tubular from the top down, rather than from the bottom up, so that the tool can be more easily retrieved.
The disadvantages of the prior art are overcome by the present invention.